The present invention is directed to a centrifuge tube and, more particularly, is directed to a thick walled polymer centrifuge tube having a circumferential groove that enhances partitioning of the tube subsequent to centrifugation.
The investigative analysis of various fluid samples requires a separation of components or fractions in fluid samples using centrifugation. It is important that no subsequent inherent contamination occurs between the separated components in the sample within the same centrifuge tube. When the separated fractions have a tendency to adhere to the interior of the centrifuge tube wall surface, a portion of the separated fraction may maintain adherence to the tube wall when the tube is returned to an upright position after centrifugation. This could cause subsequent contamination between the fractions as they are removed from the centrifuge tube.
In some instances, especially with a smaller centrifuge tube, it is desirable or more convenient to not use a tube cap or seal. However, the open end of a centrifuge tube is not as structurally strong as it is with a tube cap in place. Consequently, during centrifugation the open end of the tube without a tube cap might deform or bend. To avoid any possible deformation at the open end of the tube the thickness of the tube wall is increased to provide inherent strength during centrifugation. Thick walled centrifuge tubes do not require a tube cap to provide strength to the open end of the tube.
When it is desirable subsequent to centrifugation to separate the fraction bands and prevent contamination, a typical approach has been to utilize some type of slicer blade to cut through the tube and partition the tube between the respective separated bands of fractions. While slicing thick wall centrifuge tubes the blade tends to wander or not follow the precise intended path. In some instances the blade may break because certain thick wall tubes are made of a relatively hard polymer that has been virtually impossible to slice. Because high forces are required to force the blade through the full tube section, the blade life is relatively short.
In the prior art, tube slicing has occurred using visual alignment on the tube exterior to position the blade. However, this approach may cause problems when one desires a high degree of precision and accuracy because of the inherent dimensional inconsistencies in the visual alignment approach on the outer surface of the tubes that reduces the accuracy of partitioning for the internal volumes.
Once the tube is fully partitioned, the upper portion of the tube having a separated fraction band can be subjected to various manipulations such as dilution, mixing and removal. However, quite often there may be some type of leakage which occurs between the blade and the upper portion of the partitioned tube causing possible loss of the desired sample as well as possible leakage and contamination of a lower fraction which is in the bottom portion of the tube.